Which security task involves protecting the main body while also observing and reporting information?

The task that involves protecting the main body while also observing and reporting information is known as "Screen." This function is essential in military and tactical operations as it allows a unit to maintain security while simultaneously gathering intelligence on the enemy's movements or intentions.

In this context, the "Screen" operates by positioning units in a way that provides a protective barrier while ensuring that the unit remains aware of surrounding threats. This dual capability is crucial for making informed tactical decisions and maintaining operational effectiveness. By establishing a screen, a unit can protect its main elements from surprise attacks while keeping watch for enemy activity, thereby allowing command to anticipate and respond to potential threats effectively.

Other tasks such as guarding, covering, or area security have different primary focuses. Guarding typically involves static protection of specific assets, while covering more often refers to providing fire support for friendly entities. Area security generally pertains to securing a larger geographic space without the same emphasis on observation and reporting. Each of these tasks serves its purpose, but the definition of screening uniquely aligns with the combination of protection and intelligence gathering.